feat(战斗系统): 改进敌人生成逻辑以围绕玩家位置生成

修改Wave.spawn方法以接受中心点参数，使敌人生成位置围绕玩家
在Starter和MakeFeed面板中调用spawnWave时计算玩家中心位置
重构EntityBase添加getPlayers方法获取所有玩家实体
重命名WorldManager.nextWave为doNextWave以更清晰表达意图

scripts/Contents/Panels/MakeFeed.gd

@@ -50,7 +50,11 @@ func updateValue():
 	countLabel.text = str(UIState.player.fields[FieldStore.Entity.FEED_COUNT_CAN_MADE] - selectedCount)
 	needBB.count = refreshNeedBaseballCount
 func finish():
-	WorldManager.rootNode.spawnWave()
+	var center = Vector2.ZERO
+	for player in EntityBase.getPlayers():
+		center += player.position
+	center /= len(EntityBase.getPlayers())
+	WorldManager.rootNode.spawnWave(center)
 	UIState.closeCurrentPanel()
 func regenerateCards():
 	updateValue()

scripts/Contents/Panels/Starter.gd

@@ -64,7 +64,7 @@ func startSingleplayerGame():
 	MultiplayerState.isMultiplayer = false
 	MultiplayerState.playerName = playerNameInput.text
 	EntityBase.generatePlayer(playerNameInput.text)
-	WorldManager.rootNode.spawnWave()
+	WorldManager.rootNode.spawnWave(Vector2.ZERO)
 	UIState.closeCurrentPanel()
 
 func _ready():